Method of sharpening drills



Bees 7 1926,

C. H. STEPHENS METHOD OF SHARPENING DRILLS Filed April 26, 1926 as, M.M

fi atei'ited Dec. 7, 1926.

nairso STATES PATENT OFFICE.

CHARLES HEIIRY STEPHENS, OF STAMBAUGH, MICHIGAN, ASSIGNOR TO OGLEBAY,

NORTDN & COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METHOD OF SHARPENING DRILLS.

Application filed April 26,

This invention relates to methods of sharpening drills and moreparticularly to methods that are especially adapted for use insharpening earth drills that are commonly used in mining operations.

It is one of the objects of the invention to provide a comparativelysimple and efficient method of sharpening drills thatwill insurereliable and uniform results and be capable of being performed withcompara ively simple and inexpensive equipment.

Other objects ofthe invention and the features of novelty will beapparent from the following description taken in connection with the.accompanying drawings, of which: 7

Figs. 1 to 6 are side elevations of a drill at ditferentstages in thesharpening opera;

tion.

Fi 7 is a side elevation of a pair of dies used in practicing myimproved method, the drill being shown in position therein.

Fig. 8 is a plan of the working face of one of the dies shown in Fig. 7

Fig. 9 is a rear elevation thereof.

Fig. 10 is a side'elevation of the trimming dies with the drill shown inposition therein.

Fig. 11 is a plan of the working face of, the lower die shown in Fig.10.

Fig. 12 is a plan of the working face of the upper die shown in Fig. 10,and

Fig. 13 is a side elevation of the drill point after the completion ofthe sharpening operations.

The stock used in making drills of the class referred to is of thetwisted form shown in Fig. 1. In practicing my improved method eitherfor the purpose of resharpening a drill or for forming a. new point on apiece of raw stock one end of the twisted rod is flattened, while hot,by any suitable tools such as are commonly used by. a blacksmith forthat purpose, so as to form the end, to be pointed, substantially asshown in Fig. 2. Thereafter the flattened portion is upset and thisoperation may be conveniently performed by st ilring the end of the rod,with considerable force, against an anvil or a heavy metal block, in themanner in which such upsetting operations are commonly performed by a'blacle' smith. This has the effect of widening the flattened portion asshown in Fig. 3.

The side edges of the flattened end are then symmetrically tapered asshown in 1926. Serial No. 104,552.

Fig. l and provided with spaced gaugemarlrs which are oppositelyarranged in pairs. One corner of the flattened end is then trimmed offfrom one of the gaugemarks On a line that is inclined with respect tothe axis of the drill, the out being also beveled with respect to thesides of the flattened portion as shown in Fig. 5. The opposite corneris then trimmed off in a simi-. lar but reverse manner so as to form thepointed end shown in Fig. 6, with the edges of the point oppositelybeveled as required for drilling operations.

It is preferable to perform the various operations, above referred to,on a power hammer in order to expedite the work and in order to be ableto use dies which will uniformly sharpen different drills. In Fig. '7the anvil of a power hammer is indicated at and the movable head orhammer at '21. A die block 22 is secured on the anvil 20, in anysuitable manner, and a companion block 28 is secured to the head 21.Each of these blocks has a substantially flat working face 24 a portionof which may be roughened as indicated at 25 and these faces areemployed for the purpose of flattening the stock as shown in Fig. 2. Onecorner of each of the blocks 22 and 23 is cut away as shown at 26 andformed with an inclined working surface 27, these surfaces co-operatingto provide the tapered edges of the flattened portion as shown in Fig.7. The surfaces 27 are provided with transversely extending indentations28 in the portions thereof which operates on the edges of the drill,these indentations being oppositely arranged in pairs and forming marksor ridges in the tapered edges which serve as gauge-marks in thesubsequenttrimming operations.

The lower trimming die or shear blade is shown at 29 in Fig. 10, thisblade being secured in a holder 30 that is attached to the anvil of thepower hammer. The upper shear blade is indicated at 31 and is carried inthe holder 32 that is attached to the movable head or hammer, the blades.29 and 81 being diagonally positioned, with reference to the axis ofthe drill which is shown at 33 in Fig. 10. i

The drill is held in. an upperly inclined position on the blade 29 withthe desired gauge-mark 3-1 in line with the cutting edges of the blade.By this arrangement a trilit) angular piece is trimmed from one cornerof the end of the drill to form one edge of point as shown on 35, Fig.13. By having the drill arranged in the inclined position as shown inFig. 10, the edge 35 is beveled with respect to the opposite sides ofthe drill point. After this trimming operation, the drill is turned 180to similarly but reversely trim off the opposite corner, thereby tormingthe edge 36. This completes the sharpening operations. To resharpen adull drill the operations are identical as for making a drill :i'rom rawstock.

1n producing diflerent drills in the manner above explained the samegauge-marks will appear thereon, but When drills of different gauges andlengths are produced, different auge-marks will be utilized in thecorner trimming operations.

Having thus described my invention, I claim:

1. The method of sharpening drills which consists in flattening andspreading the end to be sharpened, tapering the flattened portion fromthe end inwardly toward the shank of the drill, forming a series ofgaugemarks on each of the side edges of the tapered portion with themarks or one series arranged directly opposite the marks of the otherseries, trimming oti' one corner of the flattened end on aline from thedesired gauge-mark to the intersection of the drill axis With the end ofthe flattened portion and in a plane that is inclined With respect tothe sides of the flattened portion, and then similarly but reverselytrimming oil the opposite corner of the flattened end and therebyforming a point having oppositely beveled edges. 7 i

2. The method of sharpening drills Which consists in providing adjacentthe end of the drill a flattened portion which tapers inwardly from theend toward the shank and the opposite edges or which have a pluralityoi. oppositely arranged gauge-marks, trimming off one corner of the endportion on a diagonal line from one gauge-mark to the end of theflattened portion, and on a bevel with respect to the sides of saidflattened portion, and then similarly but reversely trimming oh theopposite corner of the flattened portion and thereby forming a pointhaving oppositely beveled edges.

In testimony whereof, I hereunto afliX my signature.

CHARLES HENRY STEPHENS.

